The development of MEK inhibitors highlights this point [72]: since activated MEK1 and MEK2 phosphorylate and activate ERK (MAPK1), the differential deregulation of MAPK1 in AC (inactivated) and SqCC (activated) tumors may be an important consideration in determining the efficacy of this treatment against lung cancer subtypes [79]. This evidence concerns the gene MAP2K1 and lung cancer.